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A lift starts from rest. Its acceleratio...

A lift starts from rest. Its acceleration is plotted against time. When it comes to rest its height above its starting point is

A

`20 m`

B

`64 m`

C

`32 m`

D

`36 m`

Text Solution

Verified by Experts

The correct Answer is:
B
At 4s
`u=at=8m//s`
`s_1=1/2at^2=1/2xx2xx4^2=16m`
From 4s to 8s
`a=0, v=constant=8m//s`
`:. s_2=vt=(8)(4)=32m`
From 8s to 12s
`s_3=s_1=16m`
`:. s_(Total)=s_1+s_2+s_3=64m`
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